Projection type display unit having a curved housing

ABSTRACT

A cabinet of a projection type display unit includes a base cabinet on which main component parts are mounted, and a top cover made from sheet metal which is mounted so as to cover the base cabinet, wherein a rear face portion of the top cover is formed in the shape of a curved surface being laid-down U-shaped in side view. The U-shaped curved surface is formed on an ergonomic basis, so that the rear face portion can be gripped securely even with one hand. On the back side of the top cover, bosses are integrally formed by use of a resin which is a different material from the sheet metal of the top cover, and the base cabinet and the top cover are fixed by fastening screws to the bosses from the base cabinet side.

CROSS REFERENCES TO RELATED APPLICATIONS

The present invention contains subject matter related to Japanese PatentApplication JP 2005-154149 filed in the Japanese Patent Office on May26, 2005, and Japanese Patent Application JP 2005-261242 filed in theJapanese Patent Office on Sep. 8, 2005 the entire contents of whichbeing incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a projection type display unit suchthat an image obtained by irradiating a light valve, or valves, withlight from a light source is projected onto a screen, or the like, fordisplaying the image, particularly to a heat release structure for aprojecting type display unit.

A projection type display unit, generally called a video projector, hasa configuration in which a light source, an optical unit including lightvalves, and a projection lens, and a cooling section for cooling thelight source and the optical unit are incorporated in an armor cabinet(see, for example, Japanese Patent Laid-open No. 2003-241314).

The projection type display unit is a unit in which an image obtained byirradiating the light valves in the optical unit with light emitted froma lamp serving as the light source is projected onto a screen by theprojection lens, thereby displaying the image.

SUMMARY OF THE INVENTION

Such projection type display units have come to be frequently used alsofor electronic presentation attendant on the spread of PCs (personalcomputers). Among these display units, a projection type display unitexcellent in portability as an image output device for a notebook typePC or the like, particularly, has come to be keenly requested.

Considering the projection type display units in related art from thispoint of view, they are not structured taking portability intoparticular account, so that in moving such a projection type displayunit in related art, it is a general practice to carry the display unitby gripping appropriate portions of the armor cabinet with both hands.

Thus, the projection type display unit in related art has been verytroublesome to carry because it is necessary to carry the display unitby gripping it with both hands. In addition, where it is intended tocarry the display unit by gripping it with one hand irrationally, thedisplay unit is difficult to grip because the armor cabinet is large inthickness. Besides, since the armor cabinet is generally angular inshape, the gripping depth to fingertips in gripping the armor cabinet isso small that the state of being gripped by one hand is instable, sothat the display unit cannot be carried with assurance.

The present invention has been made in consideration of theabove-mentioned points. Accordingly, it is desirable to provide aprojection type display unit which is of a thin type and excellent inportability so that it can be carried in a stable state even whengripped with one hand.

According to an embodiment of the present invention, there is provided aprojection type display unit including a light source, an optical unitincluding a light valve and a projection lens, and a cooling section forcooling the light source and the optical unit, the light source and theoptical unit as well as the cooling section being incorporated in anarmor cabinet, wherein the armor cabinet includes a base cabinet onwhich the light source, the optical unit and the cooling section aremounted, and a top cover composed of a sheet metal and so mounted as tocover the base cabinet; the base cabinet is provided on the front sidethereof with an opening for the projection lens; and a rear face portioncomposed of the top cover on the opposite side of the opening for theprojection lens is formed in the shape of a laid-down U-shaped curvedsurface.

According to another embodiment of the present invention, there isprovided a projection type display unit including a light source, anoptical unit including a light valve and a projection lens, and acooling section for cooling the light source and the optical unit, thelight source and the optical unit as well as the cooling section beingincorporated in an armor cabinet, wherein the armor cabinet includes abase cabinet on which the light source, the optical unit and the coolingsection are mounted, and a top cover composed of a sheet metal and somounted as to cover the base cabinet; a resin-made boss is projectinglyprovided on the back side of the top cover; and a screw is fastened tothe boss from the base cabinet side to thereby fix the base cabinet andthe top cover.

In the projection type display unit according to the present inventionconfigured as above, the top cover composed of the sheet metal isadopted to constitute a part of the armor cabinet, whereby the armorcabinet can be reduced in thickness, a great effect on thinning thedisplay unit can be obtained, and the display unit is made to beadvantageous to carry.

Besides, in the present invention, the rear face portion composed of thetop cover is formed in the shape of a U-shaped curved surface, wherebythe portion can be ergonomically fitted to a palm when gripped by hand,and it becomes possible to grip the portion deeply to fingertips, and tosecurely grip the portion even by one hand. Thus, a projection typedisplay unit excellent in portability can be provided.

In addition, the top cover in the projection type display unit has theresin-made bosses on the back side thereof, and the screws are fastenedto the bosses from the base cabinet side to thereby fix the base cabinetand the top cover. Therefore, there are no projecting parts on thesurface of the top cover, so that carrying of the display unit would notbe hampered by such projecting parts, which is much advantageous forenhancing the portability of the display unit. Furthermore, the absenceof projecting parts on the surface of the top cover makes it possible toadopt any of a diversity of designs, and to enhance the degree offreedom in designing.

Besides, in the projection type display unit of the present invention,the bosses on the back side of the top cover are made of a resin whichis different from the sheet metal, so that there is no possibility thatcutting chips generated from the bosses at the time of fastening thescrews into the bosses might adversely affect a power circuit or thelike inside the display unit.

The above and other objects, features and advantages of the presentinvention will become apparent from the following description andappended claims, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a projection type display unit accordingto an embodiment of the present invention;

FIG. 2 is a front view of the projection type display unit according tothe embodiment;

FIG. 3 is a left side view of the projection type display unit accordingto the embodiment;

FIG. 4 is a right side view of the projection type display unitaccording to the embodiment;

FIG. 5 is a bottom view of the projection type display unit according tothe embodiment;

FIG. 6 is a plan view showing the inside structure of the projectiontype display unit according to the embodiment;

FIG. 7 is a perspective view of a top cover in the projection typedisplay unit according to the embodiment of the present invention;

FIG. 8 is a perspective view showing the shape of each boss projectinglyprovided on the back side of the top cover in the projection typedisplay unit according to the embodiment;

FIG. 9 is an illustration of the condition where the projection typedisplay unit according to the embodiment is gripped by one hand;

FIG. 10 is a side sectional view showing the structure in the vicinityof an exposing portion of a projection lens in the projection typedisplay unit according to the embodiment;

FIG. 11 is a vertical sectional view showing the structure in thevicinity of an exposing portion of a projection lens in the projectiontype display unit according to the embodiment;

FIG. 12 is a schematic diagram showing the inside structure of theprojection type display unit according to the embodiment;

FIGS. 13A and 13B are schematic diagrams showing a cooling structure ofthe projection type display unit according to the embodiment;

FIG. 14 is a perspective view showing the layout configuration of a lampplate in the projection type display unit according to the embodiment;

FIG. 15 is a bottom view showing the condition where a lamp lid isremoved, in the projection type display unit according to theembodiment;

FIG. 16 is a plan view, as viewed from the back side, of the lamp lidmounted in the projection type display unit according to the embodiment;and

FIG. 17 is a vertical sectional view showing the mounting structure ofthe lamp lid in the projection type display unit according to theembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, an embodiment of the projection type display unit according to thepresent invention will be described in detail below, referring to thedrawings. FIGS. 1 to 5 show the appearance of the projection typedisplay unit in this embodiment, wherein FIG. 1 is a perspective view,FIG. 2 is a front view, FIG. 3 is a left side view, FIG. 4 is a rightside view, and FIG. 5 is a bottom view. In addition, FIG. 6 is a planview showing the inside structure of the projection type display unit inthis embodiment.

The projection type display unit 1 shown here is a video projector whichis of a small and thin type having a B5 size with a thickness of 50 mmor below, and in which light-weight is realized to have a weight ofabout 1.8 kg.

As shown in FIG. 6, the projection type display unit 1 has aconfiguration in which a lamp unit 29 containing a lamp 28 as a lightsource, and an optical unit 30 including three color light valves 44(R),44(G), 44(B) and a projection lens 49 are incorporated in an armorcabinet 2. An image obtained by the light valves 44(R), 44(G), 44(B)with light emitted from the lamp unit 29 is projected through theprojection lens 49 onto a screen, thereby displaying the image.

First of all, the armor configuration of the projection type displayunit 1 will be described. The armor cabinet 2 of the projection typedisplay unit 1 is composed of a base cabinet 3 onto which insidecomponent parts such as the optical unit 30 are mounted, and a top cover4 so mounted as to cover the base cabinet 3. Here, the base cabinet 3 isa die-cast product formed from a metallic material such as magnesium andaluminum, or is a resin molding formed from a hard resin material, andconstitutes a bottom face portion, left and right side face portions,and a front face portion of the armor cabinet 2. On the other hand, thetop cover 4 is a worked sheet metal product produced by drawing a sheetmetal of an aluminum alloy or the like, and constitutes an upper faceportion and a rear face portion of the armor cabinet 2.

The top cover 4 is fixed, in the state of being mounted on the basecabinet 3, by screws 18 and 19 from the bottom side of the base cabinet3.

As shown in FIG. 2, the projection lens 49 is exposed through atransparent protective plate 20 to a front panel 3 a constituting afront face portion of the armor cabinet 2, and image light is projectedfrom the projection lens 49 onto a screen. Here, the transparentprotective plate 20 is disposed to be flush with the front panel 3 a,and the projection lens 49 is hermetically sealed and protected by theprotective plate 20. Further, on the inside of the protective plate 20,a projection distance detecting sensor 24 a, 24 b for auto-focusing isprovided at a position proximate to the projection lens 49, by way of asemi-transparent member 21.

At a left side face 3 b of the base cabinet 3, an operating part 6 and aterminal part 7 are concentratedly disposed, as shown in FIG. 3. Here,the operating part 6 is configured to have a power switch button 6 a, aninput signal changeover button 6 b, an auto-focus changeover button 6 c,a tilt adjustment button 6 d, a zoom adjustment button 6 e, a focusbutton 6 f and the like, and the terminal part 7 is configured to have apower cord connection terminal 7 a and a picture signal input terminal 7b. On the other hand, at a right side face 3 c on the opposite side ofthis, exhaust ports (louvers) 10 for axial fans 9 for discharging theheat of the lamp 28 as a light source are provided, as shown in FIG. 4.

A bottom face 3 d of the base cabinet 3 is provided with fixing legs 11at left and right positions of a rear face portion, and with anexpansion leg 12 at a front central position, as shown in FIG. 5. Theexpansion leg 12 is expanded and contracted so as to project outwardfrom and retract inward from the base cabinet 3, and an adjustment ofprojection angle of the display unit (tilt adjustment) is conductedthrough the movements of the expansion leg 12. In addition, the bottomface 3 d of the base cabinet 3 is provided with an intake part 13 for asirocco fan serving as a cooling section and with a multiplicity ofventilation holes 14, and a resin-made lamp lid 15 for closing anopening for replacement of the lamp unit 29 as the light source isattached to the bottom face 3 d by screws 16. The lamp lid 15 isprovided with a multiplicity of exhaust heat holes 17 for dischargingthe heat generated in the lamp unit 29.

In the projection type display unit 1 in this embodiment with theabove-described armor configuration, the top cover 4 constituting theupper face portion and the rear face portion of the armor cabinet 2 isproduced by blanking an about 1 mm thick sheet metal by a press anddrawing the blanked sheet metal. As the material of the top cover 4,there is preferably used an aluminum alloy as a metallic material whichhas a required strength for enduring as the armor of the projection typedisplay unit 1 (in this embodiment, a flexural strength of not less than15 kgf (147 N)) and which is light in weight and excellent in heatradiating property (thermal conductivity). As shown in FIGS. 7 and 8, aplurality of bosses 5 for screwing the top cover 4 to the base cabinet 3are projectingly provided on the back side of the top cover 4.

The bosses 5 are molded integrally with the sheet metal of the top cover4 by outsert molding, from a resin material being different from thematerial of the sheet metal (aluminum alloy) of the top cover 4,preferably a hard resin material such as PBT (polybutyleneterephthalate). In this case, a surface of the sheet metal is providedwith fine recesses and projections on the nanometer level by a nano-moldtechnology (NMT) process so as to permit the resin to enter into therecessed and projected surface, whereby a bonding property based on akey structure with the resin is provided so that the resin is molded inthe state of being firmly attached to the surface of the sheet metal. Inthis structure, the strength of fixation of the plurality of bosses 5 tothe top cover 4 can be maintained inexpensively and assuredly.

The plurality of bosses 5 are provided at such positions as not tointerfere with the component parts in the inside of the display unit.Each of the bosses 5 is provided at its base end portion with a pedestalpart 5 b greater in diameter than a boss body portion 5 a, whereby thearea of joint to the top cover 4 is enlarged, and a sufficient fixationstrength is secured. Furthermore, resin runner parts 5 c are extendedfrom the pedestal part 5 b, whereby the area of fixation of the boss 5to the top cover 4 is further enlarged. Besides, in this configuration,when the plurality of bosses 5 are interconnected by the resin runnerparts 5 c, the strength of fixation of the bosses 5 to the top cover 4is further increased, and the plurality of bosses 5 can be molded usinga single gate at the time of molding, so that there is generated themerit that the molding die can be simplified in structure. Incidentally,the bosses 5 may not necessarily be molded by the above-mentionednano-mold technology process; for example, the bosses 5 may beintegrally fixed to the top cover 4 by welding or by use of a strongadhesive.

In mounting the top cover 4 having the bosses 5 onto the base cabinet 3,the top cover 4 is put on the base cabinet 3. Then, in this condition,an end portion on the rear side of the top cover 4 is fixed to thebottom face 3 d of the base cabinet 3 by the screws 18, and the screws19 are fastened to the bosses 5 from the side of the bottom face 3 d ofthe base cabinet 3, whereby the base cabinet 3 and the top cover 4 arefixed.

Since the top cover 4 is made of a sheet metal, it is superior to aresin or the like in strength and heat radiating property; thus, thisconfiguration is preferable for adoption for the armor cabinet 2 of theprojection type display unit 1 as in this embodiment, and has a loweringeffect on the inside temperature. With the sheet metal top cover 4adopted, in the projection type display unit 1 according to thisembodiment, the upper face portion of the armor cabinet 2 can beminimized in thickness, which contributes greatly to the achievement ofa super-thin configuration with a thickness of 50 mm or less. With thesuper-thin configuration thus achieved, the projection type display unit1 in this embodiment can be carried while easily gripped with one hand,which is advantageous on a portability basis.

Furthermore, for enhancing portability, the projection type display unit1 in this embodiment has a structure in which, as is clear from theabove-mentioned armor configuration, the operating part 6 and theterminal part 7 are concentratedly disposed at one side face (left sideface) of the armor cabinet 2, while the side face (right side face) onthe opposite side is provided with the exhaust port 10 for dischargingthe heat generated in the lamp unit 29, and no parts are disposed at therear face portion on the opposite side of the opening for the projectionlens 49 exposed to the front panel 3 a so that the portion is easilyheld by gripping it with hand. The rear face portion of the armorcabinet 2 is composed of the sheet metal top cover 4 as above-described,and, particularly in the projection type display unit 1 according tothis embodiment, the rear face portion 4 a of the top cover 4 is formedin the shape of a laid-down U-shaped curved surface as viewed sideways.

Thus, the projection type display unit 1 in this embodiment isconfigured to have a thickness of 50 mm or less and has the rear faceportion 4 a of the top cover 4 formed in the shape of the U-shapedcurved surface, whereby the portion can be securely gripped with onehand, as shown in FIG. 9. Specifically, where the rear face portion 4 aof the top cover 4 has a general angular shape, the depth of grip to thefingertips is small, so that the state of being gripped with one handwill be instable. In this embodiment, on the other hand, the rear faceportion 4 a of the top cover 4 is formed in the shape of the U-shapedcurved surface, the portion fits to the palm favorably on an ergonomicbasis, and the grip on the display unit ranges to the fingertips, sothat the display unit can be gripped securely and assuredly even withone hand.

In this configuration, the rear face portion 4 a of the top cover 4 ispreferably formed in a circular arc shape with a radius R of about onehalf of the thickness T of the armor cabinet 2 (R=½×T), or may be formedin the shape of a continuous curve such as a parabola and an ellipse.This makes it possible to realize a curved surface shape just fitted tothe shape of a palm at the time of holding the display unit by hand, andto enhance the portability of the display unit.

Since the top cover 4 is produced by drawing a sheet metal, the curvedsurface shape can be easily obtained. In addition, since the top cover 4has the resin-made bosses 5 on the back side thereof and is screwed tothe base cabinet 3 side at the bosses 5, no projecting parts are presenton the outside surface of the top cover 4, and hampering of the carryingof the display unit by such projecting parts can be obviated, which ismuch advantageous for enhancing the portability. Besides, since the topcover 4 is produced from a sheet metal by drawing as above-mentioned,generation of a parting line on the split line of dies as experienced inthe case of a resin molding is obviated, so that a projection typedisplay unit with a streamlined appearance design can be provided.Furthermore, in this projection type display unit, the absence ofprojecting parts or the parting line on the outside surface of the topcover 4 makes it possible to adopt any of a diversity of designs, and toenhance the degree of freedom in designing.

Furthermore, in this projection type display unit, the bosses 5 forscrewing the top cover 4 are formed from a resin which is an insulatingmaterial and different from the material of the sheet metal (aluminumalloy), so that there is no fear that cutting chips generated from thebosses 5 at the time of fastening the screws 19 to the bosses 5 mightadversely affect a power circuit and the like inside the display unit.In addition, since the bosses 5 are molded integrally with the top cover4 by outsert molding and are integrated with the top cover 4 with asufficient fixation strength by a nano-mold technology process, there isno need for fixing members or an adhesive or the like for fixing thebosses 5 to the top cover 4, so that it is possible to reduce the numberof component parts, to enhance workability, and to obtain improvingeffects on an environmental basis.

FIGS. 10 and 11 show the structure of the vicinity of the exposingportion of the projection lens 49 in the front panel 3 a. As shown here,in the display unit according to this embodiment, a transparentprotective plate 20 fitted in position to be flush with the front panel3 a is disposed on the front side of the projection lens 49, so that thefront side of the projection lens 49 is hermetically sealed by theprotective plate 20, and the projection lens 49 is protected by theprotective plate 20.

The protective plate 20 is formed of a transparent resin or glass, whichis provided with AR coating on the face and back sides thereof tosuppress the lowering in luminance efficiency to 1% to 2%. Theprotective plate 20 is fitted in the front panel 3 a, and is clampedbetween the top cover 4 and the base cabinet 3. The protective plate 20is provided with flange portions 20 a, 20 b at its upper and lower endsurfaces, and the flange portions 20 a, 20 b are engaged respectivelywith the top cover 4 and the base cabinet 3, whereby the protective film20 is prevented from coming off and is retained in position.Incidentally, the front panel 3 a located on the left and right sides ofthe protective plate 20 is fitted with decorative plate 22 a and 22 bfor enhancing design quality.

Furthermore, on the inner side of the protective plate 20 in the insideof the display unit in this embodiment, a plate-like semi-transparentmember 21 a little greater than the protective plate 20 is disposed. Thesemi-transparent member 21 is fixedly fused to the inner side of thefront panel 3 a, and is provided in its central portion with an openingcorresponding to the projection lens 49 so that the projection lens 49is exposed through the opening. On the inner side of thesemi-transparent member 21, a projection distance detecting sensor 24 a,24 b for auto-focusing is disposed in proximity to the projection lens49. The projection distance detecting sensor 24 a, 24 b has a lightemitting device on one side and a light receiving device on the otherside. An infrared beam emitted from the light emitting device toward ascreen is reflected by the screen, and the reflected beam is received bythe light receiving device, to thereby measure the projection distance,for automatically conducting an auto-focus adjustment of the projectionlens 49 and up and down adjustment for keystone correction.

Here, a semi-transparent resin or glass having a visible raytransmittance of 10% to 50% and a transmittance for the infrared beamfor detecting the projection distance of not less than 90%. Examples ofan optimum material for this purpose include a methacrylic resin moldingmaterial “ACRYPET”® produced by MITSUBISHI RAYON CO., LTD. With such asemi-transparent member 21 provided, the inside component parts areinvisible from outside, so that the projection distance detecting sensor24 a, 24 b can be disposed in proximity to the projection lens 49.

As above-described, the projection type display unit 1 according to thisembodiment has a structure in which the transparent protective plate 20fitted to be flush with the front panel 3 a of the armor cabinet 2 isdisposed on the front side of the projection lens 49, thesemi-transparent member 21 having the opening corresponding to theprojection lens 49 is disposed on the inner side of the transparentprotective plate 20, and the projection distance detecting sensor 24 a,24 b for auto-focusing is disposed on the inner side of thesemi-transparent member 21, whereby a simple appearance with a surfacefree of an opening for sensor or the like is realized.

In this configuration, since the projection lens 49 is protected by theprotective plate 20 assembled into the front panel 3 a of the armorcabinet 2, the projection lens 49 is prevented from being damaged andfrom adhesion of foreign matter thereto. Further, since the protectiveplate 20 is so assembled as to be flush with the front panel 3 a, dustcollection in the vicinity of the protective plate 20 is obviated, sothat hindrance of image due to adhesion of dust or the like can besuppressed.

In addition, in this projection type display unit, the front side of theprojection lens 49 is hermetically sealed with the protective plate 20,so that penetration of dust or the like into the inside of the displayunit is prevented perfectly, the path of a cooling airflow in the insideof the display unit is made stable, and cooling efficiency can beenhanced.

Besides, in this projection type display unit, a structure is adopted inwhich the semi-transparent member 21 is disposed on the inner side ofthe protective plate 20, and the projection distance detecting sensor 24a, 24 b is disposed on the inner side of the semi-transparent member 21,whereby the projection distance detecting sensor 24 a, 24 b can be laidout in proximity to the projection lens 49. Therefore, space efficiencyin the inside of the display unit is enhanced, which contributes greatlyto the reduction in the size and thickness of the display unit.

Furthermore, in this configuration, the semi-transparent member 21 hasthe flange portion 21 a projecting toward the projection lens 49, at anedge portion of the opening corresponding to the projection lens 49. Dueto the presence of the flange portion 21 a provided in thesemi-transparent member 21, in the projection type display unitaccording to this embodiment, the light of the lamp 28 inside thedisplay unit can be prevented from leaking to the front side of theprojection lens 49 as unrequired reflected light (stray light).

In addition, in this configuration, the protective plate 20 is mountedin the state of being clamped between the top cover 4 and the basecabinet 3. Therefore, in the case where the protective plate 20 has beendamaged or broken, the protective plate 20 can be easily replaced by anew one by detaching the top cover 4 from the base cabinet 3.

Now, the inside structure of the projection type display unit 1according to this embodiment will be described below. As shown in FIG.6, the projection type display unit in this embodiment has aconfiguration in which the lamp unit 29 including the lamp 28 as a lightsource, the optical unit 30 including the three light valves 44(R),44(G), 44(B) and the projection lens 49, and the sirocco fans 51, 52 and56, 57 and the axial fan 9 as a cooling section for cooling the lampunit 29 and the optical unit 30, a power circuit unit 25 for supplyingelectric power to the lamp 28 and the like, a signal processing circuitunit 26, and an operating part and terminal part unit 27, and the likeare mounted in the inside of the armor cabinet 2.

The lamp unit 29 has a configuration in which the lamp 28 is mounted inthe inside of a unit case, and can be replaced by opening the lamp lid15 at the bottom face 3 d of the base cabinet 3. As shown in FIG. 12,the optical unit 30 is configured to include a fly-eye lens 31, apolarization conversion element 32, a condenser lens 33, dichroicmirrors 34, 35, total reflection mirrors 36, 37, 38, relay lenses 39,40, field lenses 41, 42, 43, the three light valves 44(R), 44(G), 44(B)including liquid crystal panels 45 as display elements, a prism 48, theprojection lens 49, and the like.

In the optical unit 30, non-polarized white light emitted from the lamp28 is converted into linearly polarized light while passing from thefly-eye lens 31 and through the polarization conversion element 32, andis condensed by the condenser lens 33 to be uniform white light free ofluminance irregularities, and the white light free of luminanceirregularities passes through the dichroic mirrors 34, 35, to beincident on the three light valves 44(R), 44(G), 44(B).

In this case, the white light is separated by the dichroic mirrors 34,35 serving as color separation means into red light (R), green light(G), and blue light (B), and the red light passes through the relay lens39, the total reflection lens 36, the relay lens 40 and the totalreflection mirror 37 to be condensed by the field lens 41, before beingincident on the red-light light valve 44(R). In addition, the greenlight passes through the dichroic mirror 35 to be condensed by the fieldlens 42, before being incident on the green-light light valve 44(G).Further, the blue light passes from the dichroic mirror 34 and throughthe total reflection mirror 38 to be condensed by the field lens 42,before being incident on the blue-light light valve 44(B).

The three light valves 44(R), 44(G), 44(B) are each configured to havepolarizing plates 46 and 47 on the incidence side and the outgoing sideof the liquid crystal panel 45, wherein each color light is aligned asto the polarization direction by the polarizing plate 46 on theincidence side, before being incident on the liquid crystal panel 45.The liquid crystal panel 45 modulates each light by a picture signalimpressed correspondingly to each color; then, the three modulated beamsthus obtained are polarized when transmitted through the polarizingplates 47 on the outgoing side to be picture beams, which are incidenton the prism 48. In the prism 48, the picture beams in colors aresynthesized, and the synthesized picture light is projected by theprojection lens 49 onto a screen, to display a full-color image.

In the projection type display unit in this embodiment including theprojection optical system configured as above, high heat is generated inthe lamp unit 29, the vicinity of the polarization conversion element 32and the light valves 44(R), 44(G), 44(B) in the optical unit 30, and thepower circuit unit 25, so that these components must be forcibly cooledto maintain a temperature not higher than an operation assurancetemperature.

The cooling structure will be described. As shown in FIGS. 6, 12, 13Aand 13B, in the projection type display unit according to thisembodiment, the first and second sirocco fans 51 and 52 are firstmounted as a cooling section. As the first and second sirocco fans 51and 52, small-type sirocco fans of the same type are used. The siroccofans 51 and 52 in a stacked state, with an intake port 51 a of the firstsirocco fan 51 directed upward and with an intake port 52 a of thesecond sirocco fan 52 directed downward, are disposed in a space on therear side of the optical unit 30. In this case, the first and secondsirocco fans 51 and 52 are mounted onto the base cabinet 3 in thecondition where intake spaces for the intake ports inside the displayunit are sufficiently secured, and the intake of air is conductedthrough a multiplicity of ventilation holes 14 provided in the bottomface 3 d of the base cabinet 3.

In this configuration, the first sirocco fan 51 blows air through a duct53 to the lamp unit 29 and to the vicinity of the polarizationconversion element 32 in the optical unit 30 to cool them, as shown inFIG. 13A, whereas the second sirocco fan 52 blows air through a duct 54to the power circuit unit 25 to cool it, as shown in FIG. 13B.

In such a cooling section, a sufficient quantity of cooling airflow canbe secured by use of the two small-type sirocco fans, and theinstallation space inside the display unit can be suppressed to be smallby disposing the sirocco fans 51 and 52 in the stacked state; therefore,the configuration of the cooling section can contribute greatly to thereductions in the size and thickness of the projection type display unitaccording to this embodiment.

Furthermore, in such a cooling section, the first sirocco fan 51 blowsair to the lamp unit 29 and the optical unit 30, whereas the secondsirocco fan 52 blows air to the power circuit unit 25, so that the flowsof the cooling airflows inside the display unit are optimized, andefficient cooling is thereby achieved. Incidentally, the first siroccofan 51 and the second sirocco fan 52 may be disposed in the reverseconfiguration, in which the first sirocco fan 51 blows air to the powercircuit unit 25, whereas the second sirocco fan 52 blows air to the lampunit 29 and the optical unit 30; in this case, also, the same coolingeffect as above can be obtained.

As further a cooling section, in the projection type display unitaccording to this embodiment, the third and fourth sirocco fans 56 and57 are disposed respectively on the left and right sides of theprojection lens 49. The third and fourth sirocco fans 56 and 57 are laidout by effectively utilizing the spaces on the left and right sides ofthe projection lens 49. Here, the third sirocco fan 56 and the fourthsirocco fan 57 are not the same in shape but are left-right symmetricalin shape, and they are mounted onto the base cabinet 3, with theirrespective intake ports 56 a and 57 a directed toward the projectionlens 49. The intake of air into the third sirocco fan 56 and the fourthsirocco fan 57 is conducted on the lower side of the projection lens 49through a dust-filtered intake part 13 provided in the bottom face 3 dof the base cabinet 3.

In this configuration, the third sirocco fan 56 and the fourth siroccofan 57 blow air through thin-type ducts 58 and 59, which are providedalong a bottom portion of the base cabinet 3, to the vicinity of thelight valves 44(R), 44(G), 44(B) of the optical unit 30 for cooling thevicinity of the light valves 44(R), 44(G), 44(B).

By such a configuration in which the vicinity of the light valves 44(R),44(G), 44(B) of the optical unit 30 are cooled by the third sirocco fan56 and the fourth sirocco fan 57, the flows of the cooling airflowsinside the display unit are further optimized, and further efficientcooling can be achieved.

In this case, particularly in the cooling section, the sirocco fans 56and 57 in left-right symmetrical shapes are disposed, whereby thecooling efficiency can be further enhanced. To be more specific, if theleft and right sirocco fans 56 and 57 are the same in shape, the leftand the right sirocco fans are disposed in the inverted states, so thatthe respective blowing ports are located reversely in the verticaldirection, which needs ducts with complicated paths, with the resultthat air quantity is lowered due to a pressure loss in the ducts. In thecase of the cooling section in this embodiment, on the other hand, theleft and right sirocco fans 56 and 57 which are left-right symmetricalin shape are used, whereby it is made possible to use the thin-typeducts 58 and 59 with simple paths along the bottom portion of the basecabinet 3, so that the airflows from the blowing ports of the siroccofans 56 and 57 can be guided to the optical unit 30 without resistance,and the cooling efficiency is enhanced markedly.

In addition, in this configuration, the intake of air into the siroccofans 56 and 57 disposed on the left and right sides of the projectionlens 49 is conducted on the lower side of the projection lens 49 throughthe dust-filtered intake part 13 provided in the bottom face 3 d of thebase cabinet 3; therefore, intake of dust or the like is prevented bythe dust filter at the intake part 13, so that the projection lens 49and the optical unit 30 can be securely protected from dust and thelike.

Further, in the projection type display unit according to thisembodiment, for enhancing the cooling efficiency particularly in thevicinity of the lamp unit 29 which generates a large quantity of heat,the two axial fans 9 located in the vicinity of the lamp unit 29 on theinner side of the right side face 3 c of the base cabinet 3 are disposedside by side, and the hot air generated from the lamp unit 28 isdischarged through the exhaust port 10 by the axial fans 9.

Besides, in order to realize a thin form with a thickness of 50 mm orbelow and portability as in the projection type display unit accordingto this embodiment, the top cover 4 near the lamp unit 29 generating alarge quantity of heat must be kept at such a temperature that the topcover 4 can be held by hand, while minimizing the space between the lampunit 29 and the top cover 4. For this reason, in the projection typedisplay unit according to this embodiment, a lamp plate 61 which is ahighly heat conductive sheet metal product higher in thermalconductivity than air is disposed in the space between the lamp unit 29and the top cover 4, whereby it is made possible to lower thetemperature of the top cover 4.

As shown in FIG. 14, the lamp plate 61 is a sheet metal product disposedso as to amply cover the upper side of the lamp unit 29, and aheat-diffusing effect of a highly heat conductive material constitutingthe lamp plate 61 makes it possible to lower the temperature of the topcover 4 while minimizing the distance from the lamp unit 29 to the topcover 4. Further, a lowly heat conductive heat insulating sheet 62 lowerin thermal conductivity than air is adhered to substantially the wholearea of the upper surface of the lamp plate 61, and the heat-insulatingeffect of the heat insulating sheet 62 makes it possible to furtherlower the temperature of the top cover 4. In this configuration, ahighly heat conductive metal such as pure aluminum (JIS A1000) andcopper is used as the material of the lamp plate 61, whereas a vacuuminsulation material, for example, is used as the heat insulating sheet62.

In this configuration, where it is desired to suppress the temperatureof the top cover 4 to a temperature of 40° C. to 50° C. which permitsthe user to hold the top cover 4 with hand without any problem, it isnecessary to use a sheet having a thermal conductivity of 0.0044 W/mKand a thickness of about 1.5 mm as the heat insulating sheet 62 and tosuppress the temperature of the lamp plate 61 to a temperature of about70° C. to 80° C. For achieving this temperature, a material having ahigh thermal resistance and a high thermal conductivity is used for thelamp plate 61 so that the quantity of heat received from the lamp 28 isefficiently diffused in the surface directions. Here, in the case wherean extra-high pressure mercury lamp in a 165 W class, for example, isused as the lamp 28, when a material having a thermal conductivity ofabout 200 W/mK such as pure aluminum is used for the lamp plate 61, thetemperature of the lamp plate 61 can be suppressed to about 80° C. witha heat radiating area of 9000 mm²; when a material having a thermalconductivity of about 400 W/mK such as copper is used for the lamp plate61, the temperature of the lamp plate 61 can be suppressed to or below80° C. with a heat radiating area of about 6000 mm².

Thus, in the projection type display unit according to this embodiment,the lowering of the temperature of the top cover 4 is achieved whilerealizing a thin type structure in which the space between the lamp unit29 and the top cover 4 is minimized, by the heat diffusing effect of thelamp plate 61 disposed between the lamp unit 29 and the top cover 4 andthe heat insulating effect of the heat insulating sheet 62.

As for the layout in this configuration, the lamp unit 29, the lampplate 61, the heat insulating sheet 62, and the top cover 4 are laid outin this order, and, here, the lamp plate 61 formed of a highly heatconductive material is disposed between the heat insulating sheet 62 andthe lamp unit 29, so that a lowly heat conductive material beingcomparatively low in heat resisting temperature can be used for the heatinsulating sheet 62. In this case, with a metal as a highly heatresistant material used for the lamp plate 61, it is possible to copewith the purpose under the high-temperature conditions in the vicinityof the lamp unit 29.

Besides, in this configuration, the lamp plate 61 is preferably composedof a sheet metal product which has a high reflectance in addition to thehigh thermal conductivity. To be more specific, by adopting the lampplate 61 with such a high reflectance, the reception of heat due todirect light and radiant heat from the lamp 28 can be minimized, so thatthe adoption is further effective in lowering the temperature of the topcover 4.

Further, in this configuration, the lamp plate 61 is disposed so thatits heat radiating surface fronts on the space near the axial fans 9where the velocity of the cooling airflows inside the display unit iscomparatively high, whereby heat radiation at high efficiency can beachieved. To be more specific, in the space near the axial fans 9 insidethe display unit, the velocity of airflows W is comparatively as high asabout 1 m/s to 1.5 m/s due to the exhaust force of the axial fans 9,and, with the lamp plate 61 disposed so that its heat radiating surfacefronts on the space, the quantity of heat received from the lamp 28 canbe efficiently diffused, so that heat radiation at a higher efficiencycan be achieved, which contributes greatly to lowering of thetemperature of the top cover 4.

Besides, in this configuration, the lamp unit 29 has the lamp 28contained inside the unit case 29 a having a reflector on the insidethereof. Here, particularly in the projection type display unitaccording to this embodiment, the upper side of the unit case 29 a isopened in shape, and the lamp plate 61 is closely disposed so as tocover the open side, thereby functioning also as a reflector. With sucha configuration, the distance between the lamp 28 and the lamp plate 61can be minimized, which is further advantageous for thinning the displayunit.

Further, in the projection type display unit according to thisembodiment, as a heat radiation structure in the vicinity of the lampunit 29, the structure of the lamp lid 15 for replacement of the lampunit 29 is provided with a characteristic feature. The structure of thelamp lid 15 will be described referring to FIGS. 15 to 17. FIG. 15 showsthe bottom face of the base cabinet 3 in the condition where the lamplid is removed. In the condition where the lamp lid is thus removed, anopening 65 of a storage part 64 for storing the lamp unit 29 is exposedat the bottom face 3 d of the base cabinet 3, so that the lamp unit 29can be replaced through the opening 65.

The resin-made lamp lid 15 for closing the opening 65 is mounted ontothe base cabinet 3 by screws in the state of being fitted in a mountingrecess 66 at the periphery of the opening 65, and has a large area ofnot less than two times the area of the opening 65. Further, as shown inFIG. 16, a metallic radiant heat insulating plate 67 slightly smallerthan the lamp lid 15 in area is disposed on the back side of the lamplid 15, and is mounted onto the lamp lid 15, with a required gap ofabout 1 mm therebetween. A sheet of a metal (e.g., aluminum, stainlesssteel or the like) higher in thermal reflectance than the lamp lid 15 isused as the radiant heat insulating plate 67.

In the condition where the lamp lid 15 is mounted onto the base cabinet3, as shown in FIG. 17, the lamp lid 15 is mounted in the conditionwhere the radiant heat insulating plate 67 on the back side is insurface contact with the mounting recess 66 of the base cabinet 3 overan area of not less than one half of the area thereof.

Thus, in the projection type display unit according to this embodiment,the metallic radiant heat insulating plate 67 is provided on the backside of the lamp lid 15 for closing the opening 65 of the storage part64 for the lamp unit 29, so that the radiant heat insulating plate 67functions as a buffer member against the heat coming from the lamp unit29. Moreover, since a gap is present between the radiant heat insulatingplate 67 and the lamp lid 15, heat would not easily be transferred fromthe radiant heat insulating plate 67 to the lamp lid 15, so that thetemperature of the lamp lid 15 is effectively restrained from rising.

Furthermore, in this configuration, since the lamp lid 15 is mounted inthe condition where the radiant heat insulating plate 67 on the backside is in surface contact with the base cabinet 3, the heat receivedfrom the lamp unit 29 can be transferred from the radiant heatinsulating plate 67 to the base cabinet 3 and thereby dissipated. Inthis case, particularly in the configuration according to thisembodiment, the lamp lid 15 is formed to have a size of at least twotimes the size of the opening 65, and the radiant heat insulating plate67 is put in surface contact with the base cabinet 3 over an area of atleast one half of the area thereof, whereby a further efficient heatradiating effect can be obtained. As a result, the surface temperaturesof the lamp lid 15 and the base cabinet 3 are made uniform, and theinside temperature of the display unit can be stabilized.

Besides, as shown in FIG. 16, the radiant heat insulating plate 67 isprovided with a multiplicity of exhaust heat holes 68. The exhaust heatholes 68 in the radiant heat insulating plate 67 are formed at positionscorresponding to the exhaust heat holes 17 in the lamp lid 15,ventilation property is securely provided by the exhaust heat holes 17and 68, whereby stagnation of heat inside the display unit is preventedfrom occurring, and more effective heat radiation can be achieved.

By the heat radiation structure as above-described, the projection typedisplay unit according to this embodiment has been experimentallyconfirmed to have an advantage that the surface temperature of the lamplid is lowered by about 4° C.

Incidentally, in this configuration, the base cabinet 3 is preferablyformed of a metal having a required strength, being light in weight andexcellent in heat radiation property, for example, magnesium, aluminum,or titanium, or an alloy containing such a metal. This ensures that theprojection type display unit in this embodiment can be reduced in sizeand weight while maintaining the above-mentioned heat radiating effect.

While the present invention has been described referring to theembodiment above, the invention naturally is not limited to theconfigurations of the embodiment, and other various embodiments cannaturally be adopted.

1. A projection display unit comprising: a light source; an optical unitincluding a light valve and a projection lens; an operating partincluding one or more of a power switch button, an input signalchangeover button, an auto-focus changeover button, a tilt adjustmentbutton, a zoom adjustment button, and a focus button; a terminal partincluding one or more of a power cord connection terminal and a picturesignal input terminal; a cooling fan for cooling the light source andthe optical unit; and a cabinet for housing the light source, theoptical unit, the operating part, the terminal part, and the coolingfan, the cabinet comprising: a base cabinet on which the light source,the optical unit, and the cooling fan are mounted, the base cabinethaving a front side with an opening for the projection lens; a firstside face in which the operating part and terminal part are disposed; asecond side face, which is opposite the first side face, and in which anexhaust port is provided for discharging heat from the cooling fan; anda top cover mounted to cover the base cabinet, the top cover having arear face portion on the opposite side of the opening for the projectionlens; wherein the rear face portion is formed in the shape of alaid-down U-shaped curved surface, and the distance between the topcover and the base cabinet is 50 mm or less.
 2. The projection displayunit as set forth in claim 1, wherein the top cover is formed from asheet metal of an aluminum alloy.
 3. The projection display unit as setforth in claim 1, wherein the rear face portion of the top cover isformed in a circular arc shape having a radius of about one half of thethickness of the cabinet and in the shape of a continuous curve.
 4. Theprojection display unit as set forth in claim 1, wherein no operatingpart or terminal part is disposed at the rear face portion of the topcover.
 5. The projection display unit as set forth in claim 4, whereinno operating part or terminal part is disposed on the top cover of thecabinet or the second side face of the cabinet.
 6. The projectiondisplay unit as set forth in claim 4, wherein a transparent protectiveplate is provided on the front side of the projection lens such that itis flush with a front panel.
 7. The projection display unit of claim 1,wherein the cabinet further comprises: a resin-made boss projectinglyprovided on an inside surface of the top cover; and a screw fastened tothe boss from a base cabinet side to thereby fix the base cabinet andthe top cover.
 8. The projection display unit as set forth in claim 7,wherein the boss is molded integrally with the top cover by outsertmolding.
 9. The projection display unit as set forth in claim 7, whereinthe boss is provided at a base end portion with a pedestal part forenlarging the area of interface with the top cover.